The following relates to the information storage and processing arts. It finds particular application in conjunction with cataloging of legacy documents in a marked-up format such as extensible markup language (XML), standard generalized markup language (SGML), hypertext markup language (HTML), or the like, and will be described with particular reference thereto. However, it is to be appreciated that the following is amenable to other like applications.
Legacy document conversion relates to converting unstructured documents existing in formats such as Adobe portable document format (PDF), various text formats, various word processing formats, and so forth into structured documents employing a markup language such as XML, SGML, HTML, or so forth. In structured documents, content is organized into delineated sections with suitable headers and so forth. Such organization typically is implemented using markup tags. In some structured document formats such as XML, a document type definition (DTD) or similar document portion provides overall information about the document, such as an identification of the sections, and facilitates complex document structures such as nested sections.
Unstructured documents, on the other hand, provide limited or no structural information. Many documents in corporate databases, government databases, and other document repositories are in unstructured formats, either because they predate initial use of a structured document format by the owning organization, or because the software, document scanner, or other document source ordinarily outputs in an unstructured format.
There is interest in converting unstructured documents to a structured format. The motivations for converting documents are diverse, typically including intent to reuse or repurpose parts of the documents, desire for document uniformity across a database of information store, facilitating document searches, and so forth. One type of structure which is advantageous to add to an unstructured document is a table of contents. Unstructured documents often contain the text of a table of contents which provides a logical organization or framework for the content of the unstructured document, and it is advantageous to detect and integrate this logical table of contents framework into the structure of the converted structured document.
Existing methods and apparatuses for extracting tables of content from unstructured documents are generally not robust. For example, some existing approaches rely upon font differences between document headings that are indexed in the table of contents and the surrounding text. However, in certain unstructured document formats, such as plain text formats, this font information is unavailable. Some existing approaches rely upon each section indexed in the table of contents starting on a new page. Again, this assumption is not valid for many types of unstructured documents. Some unstructured formats omit pagination altogether. Even if the unstructured format provides pagination, it may be that some sections indexed by the table of contents start in the middle of a page.
The following copending, commonly assigned applications: Method and Apparatus for structuring Documents Based on Their Layout, Content and Collection (Xerox ID 20031509-US-NP, Ser. No. 11/033,016 filed Jan. 10, 2005); Method and Apparatus for Detecting Pagination Constructs Including a Header and a Footer In Legacy Documents (Xerox ID 20040273-US-NP, Ser. No. 11/032,817 filed Jan. 10, 2005); and Systems and Methods for Converting Legacy and Projecting Documents into Extended Markup Language Format (Ser. No. 10/756,313 filed Jan. 14, 2004 and since issued as U.S. Pat. No. 7,165,216) are herein incorporated by reference. Ser. No. 10/756,313 discloses systems and methods for converting legacy and proprietary documents into extended mark-up language format in which the conversion apparatus may be implemented in software on a general purpose computer or may be made of hardware with individual components.